U.S. patent number 8,979,431 [Application Number 13/778,602] was granted by the patent office on 2015-03-17 for moisture responsive irrigation method and apparatus.
This patent grant is currently assigned to Canplas Industries Ltd.. The grantee listed for this patent is Canplas Industries Ltd.. Invention is credited to Jeff Bayley.
United States Patent |
8,979,431 |
Bayley |
March 17, 2015 |
Moisture responsive irrigation method and apparatus
Abstract
An irrigation device comprising a moisture responsive barrier is
provided. At least a portion of the barrier has perforations, at
least some of the perforations are associated with a water
swellable material. The perforations are configured to open as the
water swellable material loses moisture and dries out and are
configured to close as said water swellable material is exposed to
and absorbs water, such as during a watering step. According to
another aspect the irrigation method includes the steps of
positioning a perforated barrier between a source of irrigation
water and an area to be irrigated, wherein the perforations are
associated with a water swellable material; exposing the water
swellable material to water to cause the water swellable material
to swell to close the perforations; and permitting the water
swellable material to dry, to open the perforations, whereby the
opening and closing of the perforations regulates the amount of
irrigation water being applied across the barrier in the irrigation
method.
Inventors: |
Bayley; Jeff (Midhurst,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Canplas Industries Ltd. |
Barrie |
N/A |
CA |
|
|
Assignee: |
Canplas Industries Ltd.
(Barrie, Ontario, CA)
|
Family
ID: |
49325231 |
Appl.
No.: |
13/778,602 |
Filed: |
February 27, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130272791 A1 |
Oct 17, 2013 |
|
Foreign Application Priority Data
|
|
|
|
|
Apr 17, 2012 [CA] |
|
|
2775140 |
|
Current U.S.
Class: |
405/37; 137/78.3;
47/48.5; 239/63; 405/45 |
Current CPC
Class: |
A01G
25/02 (20130101); A01G 25/06 (20130101); Y10T
137/189 (20150401) |
Current International
Class: |
A01G
25/02 (20060101); A01G 25/06 (20060101) |
Field of
Search: |
;405/36,37,43,45
;137/78.3 ;239/63 ;47/48.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pinnock; Tara M.
Attorney, Agent or Firm: Hoffmann & Baron, LLP
Claims
I claim:
1. An irrigation device comprising a moisture responsive barrier
wherein at least a portion of the moisture responsive barrier has
perforations, at least some of said perforations being associated
with a water swellable material wherein said at least some
perforations are configured to open as said water swellable
material loses moisture and said at least some perforations being
configured to close as said water swellable material absorbs water,
the opening and closing of said at least some perforations
controlling the rate of flow of water through the perforations in
accordance with local moisture conditions, wherein said moisture
responsive barrier includes a water impermeable layer on at least
one surface thereof.
2. An irrigation device as claimed in claim 1 wherein said moisture
responsive barrier is formed into an irrigation hose and said
impermeable layer is located on an inside surface of said hose.
3. An irrigation system comprising: a. an irrigation hose for
connecting to a source of water, said irrigation hose having a hose
body, at least a portion of said hose body having perforations,
said hose body being swellable to cause said perforations to open
and to close to control a flow of water through said perforations;
b. a water sensor to sense the level of water in the hose body; and
c. a shut off valve to shut off the flow of water into the hose
body from the source of water when the water sensor detects the
presence of water at a predetermined level.
4. An irrigation system as claimed in claim 3 wherein said
perforations are associated with a water swellable material, which
shrinks as it loses moisture to open said perforations and swells
as it absorbs water to close said perforations.
5. An irrigation system as claimed in claim 4 wherein said water
swellable material swells over a predetermined exposure time to
water and said swelling closes said perforations.
6. An irrigation system as claimed in claim 5 wherein said
predetermined swell time is sufficient to permit irrigation water
to pass through said perforations to water an area adjacent to said
perforations.
7. An irrigation system as claimed in claim 4 wherein said water
swellable material shrinks over a predetermined time in the absence
of water and wherein said shrinkage opens said perforations.
8. An irrigation system as claimed in claim 7 wherein said
predetermined shrink time permits said perforations to open when an
adjacent area to said irrigation hose has dried out.
9. An irrigation system as claimed in claim 3 wherein said water
sensor detects a predetermined level of water in said hose
body.
10. An irrigation system as claimed in claim 3 wherein said water
sensor detects a rate of flow of water out of said hose body
through said perforations.
11. An irrigation system as claimed in claim 3 wherein said shut
off valve is activated when said flow of water through said hose
body reaches a predetermined minimum flow rate.
12. An irrigation system as claimed in claim 11 wherein said shut
off valve remains closed for a predetermined drying out time to
permit water in said hose body to escape, and to permit said
perforations in said hose body to open.
13. An irrigation system comprising: an irrigation hose connectable
to a source of water and an inflow valve to regulate the flow of
water into the irrigation hose, wherein the irrigation hose
includes a series of perforations formed in a hose body and the
hose body is water swellable to cause said perforations to swell
shut upon exposure to water over a predetermined time.
Description
FIELD OF THE INVENTION
This invention relates generally to plant irrigation, and more
particularly relates to ground water irrigation of the type that
dispenses irrigation water for example through a hose or water
conduit directly to the soil around the roots of plants to avoid
evaporative losses and thus to conserve water for plant growth
purposes.
BACKGROUND OF THE INVENTION
Humans have been cultivating crops since before recorded time. The
earliest and most successful growing locations combined good
growing conditions, such as plenty of water and sunlight with good
fertile soil conditions. However, as the human population continues
to expand, ever more crops are required. Out of necessity crop
science advances have been made, including using fertilizer to make
the soil more fertile and advancing plant and crop genetics to
increase crop yields from the same acreage. As well many different
types of irrigation systems have been developed to extend the
amount of plantable area.
More recently global warming has become an issue. Global warming
has the potential to alter, on a large scale, weather patterns,
including the amount and location of rainfall. Predictions have
been made of reduced rainfall in certain areas and desertification
as a result in extreme cases. This could affect the ability to
raise crops in large areas of what is now arable land.
Water consumption is also an issue. As the world population grows,
more and more water is used for domestic as well as industrial
purposes. While efforts are being made to treat the waste water
that is produced, this is not always done appropriately. Water
shortages are predicted by some in the future. Further, in certain
soil conditions, surface watering can be counterproductive. For
example, in southwestern Australia, subsurface salt has been
brought to the surface by surface over watering, essentially
sterilizing large areas to conventional crop growing, by increasing
the surface salt levels to those at which crops will no longer
grow.
One solution to a lack of water for agriculture in a region is to
use large scale diversions of fresh water sources such as rivers,
such as occur in the south western states of the USA. Another
solution is to tap into underground aquifers and extract water from
deep within the earth to use on the surface to grow crops. However,
generally a location that has little or no water, such as a desert
or semi desert, is also characterized by high evaporation rates,
meaning that surface water evaporates quickly upon being exposed.
Water that evaporates is no longer available for any plants or
crops and is thus wasted from crop growing or an agricultural point
of view. A significant amount of the water used in traditional
surface sprinkler irrigation is lost through evaporation, before it
can ever be used by the plants being watered.
As a result attempts have been made to use more direct and
efficient watering methods which reduce the likelihood evaporation
such as drip irrigation. In this technique, small feeder or water
tubes are provided to each plant which drip water onto the base of
the plant. However, while efficient in reducing the amount of water
used, because it is applied in small amounts directly to the
individual plants and root systems, there are still problems with
water loss due to evaporation. For one, the rate of evaporation and
the need for water varies depending upon the weather, the
temperature, the relative humidity and the like. This, providing a
steady drip rate will result in over watering in some cases and
under watering in other cases. Providing a variable drip rate is
very difficult.
In another attempt underground water lines have been used to feed
water directly to the root systems of plants. However, these suffer
from the invasion of fibrous roots seeking water which can block
the tubes and disrupt the water distribution to the rest of the
system. Underground delivery of the irrigation water may be
preferred when the water contains bacteria, such as untreated grey
water. In this case it is preferred to irrigate the plants without
directly exposing surface plants and animals to any such
potentially harmful bacteria.
What is desired is a form of water conserving watering system and
method that is efficient in delivering irrigation water to plants,
without exposing the water to excessive evaporation, which can
deliver the correct amount to water as needed by the plant, and
which is less vulnerable to the harmful and obstructive effects of
roots and the like. Most preferably such a system would be simple
and easy to use and located underground to mitigate the harmful
effects of contaminated source water. Most preferably it would be
largely passive and yet also automatically provide the correct
amount of water that might be needed to optimize plant growth. Such
a system would need to deliver the appropriate amount of water as
and when needed according to the moisture conditions of the soil
around the plants being so watered to be the most efficient.
SUMMARY OF THE INVENTION
The present invention is directed to a water efficient and
non-evaporative irrigation system and a method of irrigating using
the same. The invention allows the water to be directed to the
plants according to the local and specific water demand of that
plant as determined by the soil moisture content. In the event the
soil and thus any plants in the soil have enough water, no more
water will be delivered by the present invention to the plant until
it needs more. This is accomplished automatically without the need
for individual sensors or automated mechanical valves at each plant
and thus provides an efficient, simple and yet elegant solution to
the need for crop and plant watering.
In one aspect the present invention provides a water source, such
as a reservoir or city water connection and a tubing network, such
as a buried tubing network, to deliver the irrigation water to a
particular subsurface area to irrigate the root systems of specific
plants or to specific subsurface soil locations. Most preferably
the tubing network is arrayed in a pattern which permits the wide
distribution of water as needed for providing water to the roots of
a crop.
The tubing network can be comprised of permeable and impermeable
portions. The permeable portions are located adjacent to the plants
to be watered and the impermeable portions are for transporting the
irrigation water between the reservoir or water source to the
permeable portions. Most preferably the permeable portions are
selectively permeable and respond to local moisture conditions,
such as the wetness or moisture content of the adjacent
soil-letting more water through when the soil is dry and less water
through when the soil is wet. Perforations are provided through the
tubing wall and a water swellable material, such as water swellable
plastic is used in association with the perforations to permit the
perforations to open when dry and to swell shut when wet. A water
level sensor can be used to detect the presence of water within the
network, say at an upstream location on the network, which will be
an indication that the perforations are closed and that no water is
getting through the perforations. This means a wet soil condition
adjacent to the perforations which have swelled shut. In this event
a main supply valve can be shut off until the water level in the
underground tubing network subsides, indicating a need for more
irrigation by reason of the dry soil. In this event the water
source can be activated again by opening the main valve and
flooding the hose network with irrigation water.
An aspect of the present invention is that the network is
self-regulating. Water will continue to drain into dry soil, until
it becomes wet enough to cause the water swellable material to
remain in sufficient contact with the moisture so as to react by
swelling and thereby to cause the perforation to shut. Thus, areas
that are damp (ie fully irrigated) to begin with will have closed
or only slightly open perforations limiting further water flow
whereas areas of dry soil will have fully open perforations to
encourage a greater volume of flow of irrigation water and leading
to a good soaking of the soil adjacent to such perforation.
Thus, according to a first aspect, the invention provides an
irrigation system comprising an irrigation hose network for
connecting to a source of water, said irrigation hose network
including at least one section having a perforated hose body, said
perforations opening and closing to control a flow of irrigation
water through said perforations, a water sensor to sense when water
is being retained in the hose network; and a shut off valve to shut
off the flow of water into the hose network from the source of
water when the water sensor detects that water is being
retained.
According to a further aspect of the present invention there is
provided an irrigation hose connectable to source of water and
having a hose body, having at least a portion of the hose body
including perforations, said perforations being associated with a
water swellable material and being substantially open when said
water swellable material is generally dry and being substantially
closed when said water swellable material has swollen upon being
exposed to water.
According to yet a further aspect the present invention there is
provided a sheet of material having at least a portion of the
material having perforations, and having a water swellable material
associated with said perforations wherein said perforations are
substantially open when said water swellable material is generally
dry and being substantially closed when said water swellable
material has swollen upon being exposed to water.
According to a further aspect of the present invention there is
provided an irrigation method comprising the steps of positioning a
perforated barrier between a source of irrigation water and an area
to be irrigated, wherein said perforations are associated with a
water swellable material; exposing said water swellable material to
water to cause said water swellable material to swell to close said
perforations; and then permitting said water swellable material to
dry, to open said perforations, whereby the opening and closing of
said perforations regulates the amount of irrigation water being
applied in the irrigation method.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will now be made to preferred embodiments of the
invention, by way of example only, by reference to the following
figures in which:
FIG. 1 shows a cross section through a watering tube according to
the present invention;
FIG. 2 is a schematic of a representative flow network according to
the present invention;
FIG. 3 shows the embodiment of FIG. 1 where the perforations are
fully swelled shut; and
FIG. 4 shows the invention of FIG. 1 where the soil surrounding the
watering tube is wet and the perforations are closed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a cross section through a watering or irrigation tube
10 according to one embodiment of the present invention. The tube
10 includes a tube wall 12 and has an inside 14 and an outside 16.
As shown the tube 10 is buried and so soil 18 is located outside of
the tube 10. Also shown under the ground surface 20 is a plant 19
with a root system 21. While the tube 10 may also be used in an
above ground application a buried application is preferred for the
reasons set out below. Water, shown as 22, is partially filling the
tube 10. Perforations 24 are also shown through which the water 22
in the tube 10 can pass, thereby wetting the soil 18 and watering
the root system 21 of the plant 19.
The tube 10 includes a tube wall portion 22 which has special
properties to allow the tube 10 to be self-regulating in terms of
how much water is passed through the perforations 24 to the plant.
In particular the tube 10 is formed from a water swellable material
associated with the perforations 24. In this description the term
associated means that the water swellable material is located in a
position and in an amount to permit the swelling properties of the
material to open and close a perforation as water is lost from the
material or absorbed by the material respectively. It will be
understood that the present invention comprehends many
configurations of water swellable material that can be associated
with the perforations to accomplish this function. In the most
preferred embodiment the tube 10 can be largely composed of the
water swellable material but in some cases it may be preferred to
simply place the water swellable material around each perforation,
such as by molding or the like and to use another less expensive or
more dimensionally stable material for the balance of the tube 10.
This might also be preferred when the other material is easier to
work with or the like. However, the most preferred form of the
invention is believed to be to form the entire tube 10 out of the
water swellable material. If the water swellable material is placed
around each perforation it may take a number of forms or shapes,
such as a circle around the perforation, a mass on one side of the
perforation, or on both sides of the perforation, or many other
shapes and configurations and all of these are comprehended by the
present invention. All that is required is that there be enough
water swellable material placed close enough to the perforation and
that the perforation be small enough so that the range of expansion
of the water swellable material, when fully swollen, is enough to
close the perforation. Also the range of contraction of the water
swellable material has to be sufficient to permit the perforation
to open when the material has shrunken.
The present invention comprehends using straight walled
perforations, but other shapes are also comprehended. For example,
the perforation may be configured with a flap which can more easily
seal the perforation when swollen. Other configurations of
perforations are comprehended, provided that as a result of the
presence of enough water the perforation can close.
The present invention optionally includes a water impermeable liner
30. The liner 30 includes perforations which are aligned to the
perforations 24 of the water swellable material forming the tube
wall 12. The liner 30 is to prevent water within the tube 10 from
being absorbed by the tube wall 22. In this manner the water
swellable material in the tube wall 22 is responsive to the water
content of the surrounding soil 18 than of the water within the
tube 10. The liner can line the inside diameter of the tube, or,
can extend also through the perforation. In this case, the liner
will be flexible and will permit the perforation to close as the
water swellable material swells.
FIG. 2 shows an irrigation network 32 according to the present
invention. The network 32 includes a source of irrigation water 34,
a water control valve 36 and a water level sensor 38. The network
will ideally be in the form of a buried network as discussed above.
Most preferably the network includes branches that run close to or
adjacent to the roots of the plants or crops that are to be
irrigated by the water system of the present invention. If the
conditions permit, the network can be sloped down away from the
source of the water 34 and the water can feed into the network by
gravity drainage. The present invention also comprehends that a
source of pressure may be provided to drive the water into the
network, such as a pump P or the like, a natural head from an above
ground reservoir or the network 32 can have a connection to a
pressurized municipal water system. As will be understood by those
skilled in the art the water system of the present invention will
achieve the best results when water can be well distributed
throughout the network and thus distributed widely and as needed to
various crops for irrigation purposes. In a higher pressure system
it may be more difficult to control the flow so low pressure
systems are preferred.
The water level sensor 38 is preferably positioned in the network
32 at a location so that when the network is full of water, this
condition can be detected. The sensor may be any form of electronic
sensor moisture sensor, or it may be a non-electronic passive
sensor such as a float switch. What is required is that the water
level in the network can be determined so that when the network is
full, the further flow of water can be shut off by actuating the
water control valve 36. Further, when the network and tubes are dry
then the valve can be opened to allow water to flow from the source
throughout the network as needed.
The operation of the present invention can now be better
understood. When the soil adjacent to the tube 10 is dry, the tube
will also over time tend to dry out. When the tube dries out, the
water swellable material will shrink opening or further opening the
perforations 24. With the water control valve 36 shut, the water
level will drop in the network 32 as the water drains out of ay of
the perforations 22 that remain open. If in any region the soil 18
is wetter, then in that region the perforations 22 will not open as
much or remain closed slowing down the local drainage rates and
permitting the water to be directed to the drier regions being
serviced by still open perforations within the network. Once the
level detector detects that the water level in the network has
dropped, then the water control valve can be opened and water
allowed for flow from the source of water into the network. Again
the driest portions of the network will have the most open
perforations allowing them to be preferentially watered. Similarly
wetter regions will require less water and in those locations the
perforations will be less open and thus restrict the amount of
water that will be allowed to pass out of the tube 10 into the soil
18. In this manner the present invention can limit over watering
the soil 18 and the plants being irrigated.
Once the soil surround the tube 10 is wet, then the water swellable
material will begin to absorb water from the soil, causing it to
swell, and thus pinching off the perforations. This is a gradual
process, and occurs over a period of time thus permitting a good
soaking of the surrounding soil. The exact amount of time can vary
by changing the type of water swellable material, the size of the
openings or the like. Thus the present invention comprehends that
the irrigation system can be tuned to match the preferred water
demands of different crops in different soil conditions, as well as
the drainage rates of different soils. This time delay can range
from minutes, to hours, to days, as required.
FIG. 3 shows the water 60 draining out of the perforations 24,
which are open. As the perforations close, shown in FIG. 4, the
water will begin to build in the network. At some point in the
watering cycle, the water flow into the network will be greater
than the water flow out of the network as more and more
perforations close. As the water level rises in the network the
water level sensor is tripped in turn causing the water control
valve to shut off. This limits further water from being placed in
the network allowing whatever residual water remains in the network
to gradually drain. As well a drying cycle will begin whereas the
soil dries out the swellable material will dry out and then begin
to shrink. As it shrinks, the perforations will open and the water
level in the network will drop until such time as the water level
sensor is again tripped allowing water from the source of water to
be sent into the network once more. As will be understood by those
skilled in the art there may be a different set point for the level
switch to open the valve to the source of water than to close the
valve. In this way the control system for the delivery of water can
be optimized and rapid open close cycles avoided.
As can now be understood the present water system is sensitive to
external factors, such as rain. In the event of a rainstorm, the
soil will be naturally wet and the water swellable material will
remain swelled and the perforations will be kept substantially
closed. Even if the water level in the network drops, the water
will be restricted from escaping from the tube 10 into an area
where the soil is already wet, due to the water swellable material
remaining in a swollen or perforation blocking state meaning that
the network will quickly fill up again and the water control valve
will be activated to shut the valve from the source of water. As
well, if there is a particular local area of the soil that remains
wet for some reason, the perforations in that location will remain
substantially closed, meaning that water will not pass out of the
tube at that location where the water is not in any event needed.
At other, dryer locations, the perforations will be more open,
allowing water to pass out of the tube to moisten such dry
soil.
The most preferred form of the present invention includes a water
swellable material that takes some time to expand and contract. In
this way there will be an ability to water a dry soil area for a
period of time before the perforations close and stop the flow of
water. In the most preferred form of the invention the time between
opening and closing can vary from a few minutes to a number of
hours. Because the water is draining out of the perforations for
only a relatively small fraction of the time, it is anticipated
that root in growth will be less of a problem with the present
invention than for underground irrigation systems where there is
always water in the system and the roots can grow into the system
seeking the water. As well the closed perforations will make it
less likely that a root will grow in through the perforation.
While a number of water swellable materials are known and may be
suitable one of the most preferred is Nylon.TM. which does absorb
water and swell. Alternatively, the water swellable material can be
a composite such as a swellable material such as wood flour in a
porous binder matrix. Alternatively, the present invention
comprehends that the water swellable material may take the form of
a separate structure which is held adjacent to the perforations
such that when it swells it closes the perforation. The present
invention comprehends that the water swellable material is exposed
to and in contact with moisture in the surrounding soil so as to
properly control the water level in the soil. However, the tubing
material may be porous, either along certain sections, or through
at least a portion of the tubing diameter so that soil moisture can
have access to the water swellable material even if it is not in
direct contact with moisture contained within the soil.
As well, the present invention comprehends allowing certain time to
elapse between watering events. Thus, once the level switch shuts
off the valve to the water supply, an override may be provided to
prevent the valve from opening until a specified period of time
elapses. The present invention comprehends that this time can vary
between a few hours to a few days to a few weeks depending upon the
plants or crops. In this way, the watering system of the present
invention can be made responsive to local conditions such as the
thirst of the crop, and the local soil drainage characteristics
which could affect how often watering was warranted or desired.
Although the foregoing discussion has focussed on the use of the
invention in a hose as part of an underground network
configuration, it will be understood by those skilled in the art
that the present invention also comprehends a sheet material form
of the invention which includes at least a portion of the material
being perforated with openable and closeable perforations, and in
the most preferred form of the invention perforations that open and
close in accordance to the presence or absence of water. In a sheet
form it may be used as a moisture restricting barrier to control
the flow of water between two locations. As a selectively permeable
barrier it acts to mitigate water flow levels to improve the
consistency of drainage for example. For example it might be used
to dampen oscillations of flow volumes where that was desirable. In
the sheet context the present invention would not be associated
with a level sensor and a source of water but would be governed by
the presence of water within the soil and as such water was flowing
through the soil and through the moisture restricting barrier
itself. Further, the sheet material could be rolled into a tube as
described above to form the hose. Alternatively the hose could be
made by being pulled out of a die, being molded or the like.
It will be understood that the foregoing description is by way of
example only and that many variations and alterations to the
invention are comprehended by this specification without departing
from the broad scope of the invention as defined by the attached
claims. Some of these variations are discussed above and others
will be apparent to those skilled in the art. For example, while
the preferred form of the invention is to use discrete
perforations, the whole rube could be made porous, in the nature of
a soaker hose. In that case the water swellable material
surrounding the many small perforations would act in the same way
as described above. Alternatively, the perforations could be made
at distinct spacings, corresponding for example with the planting
spacing for a row of crops.
* * * * *